Heterogeneity Of Physical Properties Research Articles

Personalized Vascularized Models of Breast Cancer Desmoplasia Reveal Biomechanical Determinants of Drug Delivery to the Tumor.

Desmoplasia in breast cancer leads to heterogeneity in physical properties of the tissue, resulting in disparities in drug delivery and treatment efficacy among patients, thus contributing to high disease mortality. Personalized in vitro breast cancer models hold great promise for high-throughput testing of therapeutic strategies to normalize the aberrant microenvironment in a patient-specific manner. Here, tumoroids assembled from breast cancer cell lines (MCF7, SKBR3, and MDA-MB-468) and patient-derived breast tumor cells (TCs) cultured in microphysiological systems including perfusable microvasculature reproduce key aspects of stromal and vascular dysfunction causing impaired drug delivery. Models containing SKBR3 and MDA-MB-468 tumoroids show higher stromal hyaluronic acid (HA) deposition, vascular permeability, interstitial fluid pressure (IFP), and degradation of vascular HA relative to models containing MCF7 tumoroids or models without tumoroids. Interleukin 8 (IL8) secretion is found responsible for vascular dysfunction and loss of vascular HA. Interventions targeting IL8 or stromal HA normalize vascular permeability, perfusion, and IFP, and ultimately enhance drug delivery and TC death in response to perfusion with trastuzumab and cetuximab. Similar responses are observed in patient-derived models. These microphysiological systems can thus be personalized by using patient-derived cells and can be applied to discover new molecular therapies for the normalization of the tumor microenvironment.

Incorporation mechanism of Fe and Al into bridgmanite in a subducting mid-ocean ridge basalt and its crystal chemistry

The compositional difference between subducting slabs and their surrounding lower-mantle can yield the difference in incorporation mechanism of Fe and Al into bridgmanite between both regions, which should cause heterogeneity in physical properties and rheology of the lower mantle. However, the precise cation-distribution has not been examined in bridgmanites with Fe- and Al-contents expected in a mid-ocean ridge basalt component of subducting slabs. Here we report on Mg0.662Fe0.338Si0.662Al0.338O3 bridgmanite single-crystal characterized by a combination of single-crystal X-ray diffraction, synchrotron 57Fe-Mössbauer spectroscopy and electron probe microanalysis. We find that the charge-coupled substitution AMg2+ + BSi4+ ↔ AFe3+(high-spin) + BAl3+ is predominant in the incorporation of Fe and Al into the practically eightfold-coordinated A-site and the sixfold-coordinated B-site in bridgmanite structure. The incorporation of both cations via this substitution enhances the structural distortion due to the tilting of BO6 octahedra, yielding the unusual expansion of mean <A–O> bond-length due to flexibility of A–O bonds for the structural distortion, in contrast to mean <B–O> bond-length depending reasonably on the ionic radius effect. Moreover, we imply the phase-transition behavior and the elasticity of bridgmanite in slabs subducting into deeper parts of the lower mantle, in terms of the relative compressibility of AO12 (practically AO8) and BO6 polyhedra.

Spatial Mapping of Riverbed Grain-Size Distribution Using Machine Learning

Recent alluvial sediments in riverbeds play a significant role in controlling hydrologic exchange flows (HEFs) in river systems. The alluvial layer is usually associated with strong heterogeneity in physical properties (e.g., permeability and hydraulic conductivity), which affects local HEFs and therefore biogeochemical processes. The spatial distribution of these physical properties needs to be determined to inform the numerical models used to reveal the realistic hydro-biogeochemical behaviors. Such information can be obtained based on the intrinsic link between sediment grain-size distribution and hydraulic properties where sediment texture information is available. However, grain-size measurements are usually spatially sparse and do not have adequate coverage and resolution, particularly for a relatively large domain such as the Hanford Reach of the Columbia River. In this paper, we adopted machine learning (ML) approaches for categorizing and mapping the spatial distributions of riverbed substrate grain size and filling in missing areas of substrate data using the ML models along the reach. Such ML models for substrate size mapping were trained at 13,372 locations using measured substrate sizes along with observed and simulated attributes, including bathymetric attributes (e.g., elevation, slope, and aspect ratio) from LIDAR and bathymetric surveys, and hydrodynamic properties (e.g., water depth, velocity, shear stress, and their statistical moments). An ensemble bagging-based ML technique, Random Forest, was adopted to identify the most influential factors as predictors to develop the predictive models with over-fitting issues addressed. The models were evaluated with respect to each individual substrate size class and the lumped group, and then used to generate the final substrate size maps covering all the grid cells in the numerical modeling domain.

Impact of rock type on the pore structures and physical properties within a tight sandstone reservoir in the Ordos Basin, NW China

The pore–throat systems and physical properties of tight sandstone reservoirs are complex, and deposition is thought to be a fundamental control for them. In this study, the impacts of the full ranges of rock types (from pebbly coarse sandstone to fine sandstone) on the pore structures and physical properties of the Permian tight sandstone reservoir in the eastern Ordos Basin were investigated comprehensively through a series of experiments including conventional physical testing, thin-section analysis, scanning electron microscopy, nuclear magnetic resonance analysis and high-pressure mercury injection tests. The results showed that the coarser-grained sandstones tend to have higher feldspar content and lower percentage of cements, leading to strong dissolution, weak cementation and improved porosity and permeability. The medium sandstone has the highest level of quartz and the lowest average content of feldspar, resulting in strong heterogeneity of physical properties. Only those medium sandstone reservoirs with relatively high content of feldspars have better physical properties. Additionally, the coarser-grained sandstones contain relatively large dissolution pores (nearly 200 μm), whereas the finer-grained sandstones have more intercrystalline pores with a relatively more homogeneous pore structure. The pebbly coarse sandstone and coarse sandstone reservoirs are favorable targets with best physical properties.

Surface to Groundwater Interactions beneath the City of Berlin: Results from 3D Models

Knowing the thermal and hydraulic conditions below major urban centers is of increasing importance in the context of energy and water supply. With this study, focusing on the major urban center of Berlin, Germany, we aim to gain insights on the coupling of surface water bodies to the subsurface thermal and hydraulic field investigating shallow water to deep groundwater interactions. Therefore, we use a 3D structural model of the subsurface, constrained by all available data and observations, as a base for simulations of the coupled transport of fluid and heat. This model resolves the 3D configuration of the main geological units and thus enables us to account for related heterogeneities in physical properties. Additionally, we resolve surface water body geometries with newly available data. To assess how surface water bodies interact with the deeper groundwater at different depths in the model domain, the influence of different hydraulic boundary conditions is quantified, which indicates that the coupling of surface water bodies and groundwater strongly modifies predicted groundwater circulation. Consequently, changes in subsurface temperatures are also predicted, where lakes may account for temperature differences up to ±5°C and rivers could account for up to ±1°C visible at depths ≤-500 m.a.s.l. These differences are mainly connected to changes in the advective component of heat transport caused by the modifications of the hydraulic boundary condition. Pressure-driven heat transport is most efficient where differences between hydraulic heads of aquifers and surface water bodies are highest. This study therefore illustrates the impact of surface to subsurface water interactions in an urban context.

Spatial heterogeneity of physical properties of the soils in Ukraine

Aim. To investigate structural composition (lumpiness), bulk density and penetration resistance in soils of Polissia, Forest-Steppe and Steppe. Methods. The experimental plots were allocated on the fi elds in a regular network. The measurements performed before harvesting testifi ed to an equilibrium condition of soil physi- cal properties. The data ware processed by the geostatistical method. Results. The key parameters of spatial heterogeneity (variation factors, histograms, autocorrelation function, variogrammes, 2-D and 3-D diagrams, etc.) were received. The heterogeneity of physical properties, revealed in all soils, is characterized by moderate and increased values. As a result the investigated fi elds were divided into three agrotechnological groups by qualitative parameters of their physical properties. Conclusions. The recommendations on pre-sowing or basic tillage of various intensity – without tillage (if parameters are close to the requirements of the sown culture), with moderate tillage of zone type (if parameters are close to modal values) and with tillage of the enhanced intensity (if parameters are unsatisfactory and more intensive pre-sowing tillage is required) were formulated for each group.

The physical origins of transit time measurements for rapid, single cell mechanotyping.

The mechanical phenotype or 'mechanotype' of cells is emerging as a potential biomarker for cell types ranging from pluripotent stem cells to cancer cells. Using a microfluidic device, cell mechanotype can be rapidly analyzed by measuring the time required for cells to deform as they flow through constricted channels. While cells typically exhibit deformation timescales, or transit times, on the order of milliseconds to tens of seconds, transit times can span several orders of magnitude and vary from day to day within a population of single cells; this makes it challenging to characterize different cell samples based on transit time data. Here we investigate how variability in transit time measurements depends on both experimental factors and heterogeneity in physical properties across a population of single cells. We find that simultaneous transit events that occur across neighboring constrictions can alter transit time, but only significantly when more than 65% of channels in the parallel array are occluded. Variability in transit time measurements is also affected by the age of the device following plasma treatment, which could be attributed to changes in channel surface properties. We additionally investigate the role of variability in cell physical properties. Transit time depends on cell size; by binning transit time data for cells of similar diameters, we reduce measurement variability by 20%. To gain further insight into the effects of cell-to-cell differences in physical properties, we fabricate a panel of gel particles and oil droplets with tunable mechanical properties. We demonstrate that particles with homogeneous composition exhibit a marked reduction in transit time variability, suggesting that the width of transit time distributions reflects the degree of heterogeneity in subcellular structure and mechanical properties within a cell population. Our results also provide fundamental insight into the physical underpinnings of transit measurements: transit time depends strongly on particle elastic modulus, and weakly on viscosity and surface tension. Based on our findings, we present a comprehensive methodology for designing, analyzing, and reducing variability in transit time measurements; this should facilitate broader implementation of transit experiments for rapid mechanical phenotyping in basic research and clinical settings.

Foreshock and aftershocks in simple earthquake models.

Many models of earthquake faults have been introduced that connect Gutenberg-Richter (GR) scaling to triggering processes. However, natural earthquake fault systems are composed of a variety of different geometries and materials and the associated heterogeneity in physical properties can cause a variety of spatial and temporal behaviors. This raises the question of how the triggering process and the structure interact to produce the observed phenomena. Here we present a simple earthquake fault model based on the Olami-Feder-Christensen and Rundle-Jackson-Brown cellular automata models with long-range interactions that incorporates a fixed percentage of stronger sites, or asperity cells, into the lattice. These asperity cells are significantly stronger than the surrounding lattice sites but eventually rupture when the applied stress reaches their higher threshold stress. The introduction of these spatial heterogeneities results in temporal clustering in the model that mimics that seen in natural fault systems along with GR scaling. In addition, we observe sequences of activity that start with a gradually accelerating number of larger events (foreshocks) prior to a main shock that is followed by a tail of decreasing activity (aftershocks). This work provides further evidence that the spatial and temporal patterns observed in natural seismicity are strongly influenced by the underlying physical properties and are not solely the result of a simple cascade mechanism.

The Physical Properties and their Prediction of Volcanic Reservoirs in Luxi Area of Junggar Basin, China

The physical properties of reservoirs determine the ability on accumulating hydrocarbon. As one of the unconventional hydrocarbon reservoirs, the volcanics own the different characteristics from the clastic rocks on physical properties. The study on the relationship between physical and electrical properties of deep volcanic reservoirs was conducted, using the Luxi area of Junggar basin as an example. By our study, some conclusions have been made: The heterogeneity of physical properties is strong in volcanic rocks whose porosity and permeability vary in different lithology and lithofacies; different rocks in a same well have various values of porosity and permeability, and a certain type of volcanic rock has different values of porosity and permeability in diverse wells. According to measured data, the value of porosity an permeability in erupting and effusive facies area are high, while in volcanic channel and extrusive facies as well as volcanic sedimentation facies are low. Unlike the clastic rocks, in volcanic rocks there is little relationship between porosity and permeability and all of them do not have close relationship to the buried depth. Different electrical responses have different relationship with the porosity of one certain lithology, while one certain electrical property has different responses for the porosities of different lithologies; comparatively speaking, the porosities of tuffites, breccia correlate intensively with GR, SP and AC, so these electrical parameters can be utilized to predict the physical properties. This study illustrated that the relativities between porosity and GR, AC, and SP are Por=-0.6189×GR+52.691 (R2=0.9311), Por =-0.3771×AC + 34.5 (R2=0.8876) and Por = 2.1458×SP + 79.404 (R2=0.8236).

Syn-eruptive chaotic breccia on Kos, Greece, associated with an energetic pyroclastic flow

The climax of the Kos Plateau Tuff (KPT) eruption (eastern Aegean, Greece) generated a highly energetic, coarse-grained, lithic-rich, pyroclastic flow. In most places on Kos, the deposit from this event is an ignimbrite (ignimbrite El) that comprises a basal, coarse-grained, lithic breccia and overlying pumiceous part, above a planar, strongly erosional lower contact. However, along the northern coast of central Kos, "normal" ignimbrite El overlies a hummocky, 6-m-thick layer of chaotic breccia comprising mingled-to-pervasively mixed ignimbrite El and unconsolidated sediment. The surface morphology of the chaotic breccia and its internal texture resemble those of a debris-avalanche deposit, but the breccia is neither proximal nor downcurrent of steep topography. The lower part of the chaotic breccia comprises distinct domains of unconsolidated sediment or lower KPT units that are deformed and/or mingled with pumiceous ignimbrite. The upper part is dominated by a matrix of mingled-to-pervasively mixed ignimbrite and sediment that contains sediment domains as large as 2–10 m in diameter. Such large intact allochthonous domains are best preserved at the top of the chaotic breccia and form the hummocks. The chaotic breccia formed synchronously with the passage of a highly energetic pyroclastic flow where it traversed wet, unconsolidated sediment. Shear-induced liquification, together with possible ground shaking associated with the eruption, probably caused failure. Part of the unconsolidated substrate and basal part of ignimbrite El were dislodged and resedimented a short distance (tens to hundreds of metres) downcurrent. The lower part records deformation and disintegration of the substrate induced by the overriding, shearing flow. Mingling and deformation of the poorly consolidated material occurred as a result of within-flow lateral shear. Attenuated worm burrows within the sediment domains, and pinch-and-swell and flame structures within the mingled domains, preserve evidence of shear in the lower part. The upper part was transported downcurrent above a zone of shear failure. Internal heterogeneities in physical properties resulted in variable strain rates causing some domains to be pervasively mixed while others remained intact. Intact large unconsolidated domains at the top were transported mostly above the zone of shearing.

Molar Morphology and Food Texture among Small-Bodied Insectivorous Mammals

This study investigated whether heterogeneity of physical properties in dietary items would be reflected in the molar dentitions of extant mammals that specialize on invertebrate prey. Measurements of six shearing crests were made on lower second molars in three pairs of microchiropteran species, one pair of insectivoran species, and one pair of primate species. The physical properties of prey species routinely consumed is distinctive within each of these taxonomic pairs. Hard- and soft-object feeding insectivores were statistically distinct from one another on the basis of differential development of shearing features on their molar dentitions. Specifically, soft-object feeders, those mammals that primarily consume moths, caterpillars, and worms, exhibit relatively more shearing development than do closely related taxa that have more generalized feeding patterns including large quantities of hard-bodied beetles.

Dominance and Diversity Maintenance in an Oceanic Ecosystem

Disturbance—perturbation, dispersal—reaction, and contemporaneous disequilibrium are similar theories used to explain the maintenance of species diversity in communities. These theories explicitly predict that in patches, on certain time—space scales, there should be substantial shifts in the order of species dominance. There is good evidence that these theories may explain species coexistence in terrestrial and marine systems of sessile organisms. We have tested this set of theories in a mobile pelagic system by examining the order of dominance of copepod species in samples separated in time and space, collected from °30 min to 16 yr apart, and from hundreds of metres to thousands of kilometres apart. We could not detect significant changes among the samples in rank order or in percent similarity of species abundance on any time scale, or on any space scale up to °800 km, either when all 175 species or when only the 30 most abundant were considered. There was small—scale, mesoscale, seasonal, and interannual heterogeneity in physical properties during the time we made our measurements. Although the theories are satisfactory explanations of diversity maintenance in sessile systems, our results fail to validate them in our mobile pelagic system. Because there were episodes of significant physical variability and because of the long—term species equilibrium and constancy of dominance, we believe our highly diverse community to be resilient and robust, rather than fragile. The regulatory forces are strong and almost certainly biological, rather than physical, but we cannot identify them.